Add missing dependencies on goog.array
Use in-place filtering for post-render functions
Use for loop for iterating over layers
Use in-place filtering for pre-render functions
Remove dependency on goog.array
Merge pull request #145 from elemoine/readme

Update readme.md
Use goog.now() instead of Date.now().

Date.now() is not supported in Internet Explorer up to IE 9. The goog.now()
method can be used as a replacement.
Merge pull request #147 from marcjansen/goog.now

Use goog.now() instead of Date.now().
Export map.getLayers
Merge pull request #140 from twpayne/array-clean-ups

Array clean ups
Replace ol.overlay.Overlay with ol.AnchoredElement

This commit adds several features:
- rename of class to better reflect its behaviour
- full ol.Object support
- integration with postrender event for integration with animations and
  render loop
- minimised DOM modifications
- more precise positioning
- element placed in DIV to avoid modifications to user-supplied element
- correctly handle changes to the positioning property
Adjust border-radius of zoom buttons.
Merge pull request #150 from marcjansen/zoombtn-radius

Adjust border-radius of zoom buttons.
Add tile cache expiry infrastructure
Use option object rather than positional arguments for ol.animation.create* functions
Add ol.TileCache
Use ol.TileCache in ol.source.ImageTileSource
Use ol.TileCache in ol.source.DebugTileSource
Merge pull request #133 from fredj/options-obj

ol.animation.create* functions should use options objects rather than positional arguments
Add goog.structs.LinkedMap from Closure Library